Investigation into surface and subsurface drip irrigation for jujube trees grown in saline soil under extremely arid climate

摘要

Efficient irrigation and salinity control are important issues in arid regions, and a water-saving and salt-controlling irrigation method was required. Indirect subsurface drip irrigation (ISDI) is an efficient irrigation method, which consists of a drip irrigation (DI) system above the surface of the ground and a vertical tube that is buried in the root-zone soil under the dripper of DL ISDI achieves the effect of subsurface drip irrigation (SDI), while water in DI drips into the root-zone soil through the vertical tube. The two drip irrigation methods (ISDI and DI) and irrigation factors (diameters of the vertical tube and irrigation volumes) on the distribution of water and salinity in the root zone soil as well as the quality and yield of jujube trees were studied in 2012-2013 in an extremely arid desert region in the province of Xinjiang, China. In order to determine suitable irrigation methods and modes, three levels of irrigation volume were used for both ISDI and DI, and three diameters of vertical tube were used for ISDI. The results showed that ISDI was found to be a more suitable irrigation method than DI. Under ISDI, the vertical tube diameter of 75 mm and an irrigation volume of 13-14 L plant(-1) was the more suitable irrigation mode; while the average desalination ratio in the soil layer at 0-50 cm depth at a distance of 30 cm from the vertical tube was 25.2%, the average jujube yield was 2,579 kg ha(-1), and the average irrigation water use efficiency (IWUE) was 3.48 kg m(-3). In addition, the organic acid, soluble sugar, and Vc contents of fruit quality were also high. The results are significant for the cultivation of fruit trees using highly efficient water irrigation while preventing secondary soil salinization.